Groundwater monitoring requires accurate and uniform emplacement of filter packs and seals during construction of the groundwater monitoring well in order to obtain confident representative groundwater samples and hydrological data. A proper installation system must ensure that bridging of filter pack and seal materials does not occur, particularly when installing multi-level groundwater monitoring systems.
Presently, emplacement of filter packs and seals is carried out by one of three methods: One method involves pouring materials down the annulus of the monitoring well system, followed by tamping. This method is restricted to shallow installations in large holes with small diameter wells. A second method involves continuous pouring of materials down a tremie pipe while withdrawing pipe sections. This method is very time consuming and prone to clogging. It requires at least a 1.5 inch inside diameter pipe which places restrictions on hole size and depth. A third method involves pumping of a slurry of the seal material down the hole which requires mixing and pumping equipment with special high-solids grouting materials. Also, contamination of the filter pack is common with this method.